Oil collection boom

ABSTRACT

An oil absorbing boom to be deployed across the effluent stream from a separator or settling basin on the downstream side of oil transfer operations at a seaport for the purposes of collecting and removing from the water thin films of oil such as those which sometimes escape from oil spill booms surrounding a tanker at a loading dock, and comprising an elongated flat tubular sleeve of polymer netting enclosing within itself a plurality of flat elongated slabs or bats of &#39;&#39;&#39;&#39;picker-lap&#39;&#39;&#39;&#39; fibrous polymer material such as blown polypropylene film arrayed end to end within the tubular sleeve and sufficiently spaced apart to permit accordion folding of the sleeve at fold lines between adjacent bats, with a tension-bearing rope or cable being positioned within the tubular sleeve alongside the successive plurality of absorbent bats to reinforce the structure for carrying its own weight or impact loads placing it in tension between its ends. Alternatively, a continuous, wide, flat sheet of extremely porous hydrophobic foam material such as fully reticulated polyurethane foam, suspended from overlying buoyant flotation material, is formed into a similar elongated boom deployed across a floating oil film or into a continuous endless belt repeatedly cycled through the floating oil. After trapping oil within the porosities or interstices of the boom or belt material, it is squeezed between pinch rolls to force out and recover the trapped oil, and the device is thus capable of successive repeated deployment cycles of oil recovery operation.

United States Patent 1 *July 25, 1972 Smith [54] OIL COLLECTION BOOM[72] Inventor: Millard F. Smith, PO. Box 295, Saugatuck, Conn. 06882Notice: The portion of the term of this patent subsequent to Nov. 10,1987, has been disclaimed.

[22] Filed: Jan. 27, 1970 [21] Appl. No.: 6,117

Related U.S. Application Data Primary Examiner-Reuben Friedman AssistantExaminerT. A. Granger Attorney-Robert H. Ware [57] ABSTRACT An oilabsorbing boom to be deployed across the effluent stream from aseparator or settling basin on the downstream side of oil transferoperations at a seaport for the purposes of collecting and removing fromthe water thin films of oil such as those which sometimes escape fromoil spill booms surrounding a tanker at a loading dock, and comprisingan elongated flat tubular sleeve of polymer netting enclosing withinitself a plurality of flat elongated slabs or bats of picker-lap"fibrous polymer material such as blown polypropylene film arrayed end toend within the tubular sleeve and sufficiently spaced apart to permitaccordion folding of the sleeve at fold lines between adjacent bats,with a tension-bearing rope or cable being positioned within the tubularsleeve alongside the successive plurality of absorbent bats to reinforcethe structure for carrying its own weight or impact loads placing it intension between its ends. Alternatively, a continuous, wide, flat sheetof extremely porous hydrophobic foam material such as fully reticulatedpolyurethane foam, suspended from overlying buoyant flotation material,is formed into a similar elongated boom deployed across a floating oilfilm or into a continuous endless belt repeatedly cycled through thefloating oil. After trapping oil within the porosities or interstices ofthe boom or belt material, it is squeezed between pinch rolls to forceout and recover the trapped oil, and the device is thus capable ofsuccessive repeated deployment cycles of oil recovery operation.

6 Claims, 8 Drawing Figures on. COLLECTION BOOM RELATED APPLICATION Thisapplication is a continuation-in-part of my co-pending patentapplication Ser. No. 739,231, filed June 24, 1968, now US. Pat. No.3,539,013.

BACKGROUND OF THE INVENTION The problem of spilled oil in seaports whereoil is transferred daily from tankers to shore installations or otherwaterborne petroleum transport vessels has become increasingly seriousin recent years. Pollution of harbor waters has become the subject ofnew laws and increasingly firm administrative action in many localities.Oil spill booms such as those shown 'in Millard F. Smith US. Pat. No.3,146,598 generally serve well to contain oil inadvertently spilled fromruptured hose or a leaking fitting during the normal transfer ofpetroleum to and from waterborne transport vessels. Occasional leakagepassed by conventional oil spill booms which may be caused by a localwater disturbance, such as a vessel's wake, sometimes permits the escapeof small quantities of oil from a spill which is otherwise successfullycontained. This escaping oil spreads on the surface of the water in anextremely thin film, making it very difficult to remove. The resultingdeposit of oil along shores, beaches and waterside installations createsan important source of liability for the operators of oil refineries,tankers and oil transfer installations, and the need for skimming-typeoil film recovery devices has gone long unfilled.

OBJECTS OF THE INVENTION Accordingly a principal object of the inventionis to provide an oil recovery boom capable of being convenientlydeployed downstream in the path of current-carried oil film slicks toabsorb these slicks. A further object of the invention is to providesystems and apparatus cooperating with such oil absorbing booms for theremoval of the boom carrying absorbed oil from the surface of the water,and for separating the absorbed oil from the absorbing boom which maythen be prepared for re-use, to be re-deployed as required.

Another object of the invention is to provide readilydepolyableelongated booms and belts of lightweight, highly porous material capableof entrapping and removing substantial volumes of oil from an oil slickor floating oil film. A further object is to provide such devices inself-supporting buoyant assemblies for convenient deployment andrepeated re-use.

Other and more specific objects will be apparent from the features,elements, combinations and operating procedures disclosed in thefollowing detailed description and shown in the drawings.

THE DRAWINGS FIG. 1 is a schematic plan view of a maritime oil transferterminal showing a tanker near a dock surrounded by an oil boom with anoil collection boom of the present invention deployed downstream tocollect any escaping oil;

FIG. 2 is an enlarged fragmentary elevation view schematically showingpinch roll apparatus on shore positioned to draw in the boom andseparate collected oil from it by compressive pinch roll action;

FIG. 3 is a further enlarged fragmentary perspective view, partially cutaway, showing an oil collecting boom of the present invention;

FIG. 4 is a comparable fragmentary perspective view showing thepreferred steps in the fabrication of an oil collection boom of thepresent invention;

FIG. 5 is a greatly enlarged cross-sectional elevation view of an oilcollection boom fabricated by the process illustrated in FIG. 4;

FIG. 6 is a schematic perspective view of a different embodiment of theinvention;

FIG. 7 is a fragmentary schematic perspective view of still anotherembodiment of the invention; and

FIG. 8 is a fragmentary perspective cross-sectional view of a furthermodified embodiment of the invention.

COMPRESSIBLE OIL COLLECTION BOOMS The booms of one embodiment of thepresent invention take advantage of the substantial interstitial volumeincorporated in lightweight bats of polymer fibers or blown polymer filmof such materials as polypropylene which present enormous fiber surfacearea on which oil film deposits itself when a passing current of wateron which such a bat floats carries a film of oil into contact with thebat. When this occurs, most or all of the oil film is collected upon thefibrous surfaces inside the bat, and very little oil proceeds downstreambeyond the structure.

The oil collection booms of this form of the present inventionincorporate a plurality of elongated, flat, rectangular bats of suchmaterial, which may be for example Avisun polypropylene No. 101 l, ahigh molecular weight polymer formed into fine randomly oriented fibersin a bat of fiber material referred to as picker-lap, incorporatingfibers having a 2.5 denier, 2 inch long in average length. SimilarAvisun polypropylene polymers passed through blown film apparatus atextrusion temperatures in the range between 425 and 450 F produce blownfilm which may be formed into the same type of extremely lightweightcompressible fluffy fibrous bats. Since the specific gravity ofpolypropylene is about 0.90, these bats of material are buoyant and welladapted to serve as floating oil collection structures.

In the booms of this form of the invention, such as the boom 10illustrated in the FIGURES, a greatly elongated tubular net sleeve 1 lencloses a series of wide, fiat, thin, elongated bats 12 of thisexpanded polymer material just described, as shown in FIGS. 3, 4 and 5.The net sleeve 11 is preferably formed of similar lightweight polymerfibers which may be heat-sealed in net configuration or which may bewoven or knotted like a fisherman's net in the form and spacing desired.The bats 12 are spaced apart longitudinally within the tubular sleeve 11by a distance of from two or three times their thickness to permitaccordion-folding in the manner of the accordion-folded oil spill boomshown in my US. Pat. No. 3,146,598. In the fabrication processillustrated in FIG. 4, a roll 13 of the netting material 11 is unrolledto draw a length of this material over a work station where a bat 12 islaid lengthwise along one-half of the net 11 drawn from the roll 13.Along the inner edge of the bat 12, a tension cable preferably formed ofstainless steel wire rope l4 unreeled from a storage reel 16 is alsolaid longitudinally down the central portion of the net 11 beside thebats 12. The free half of the net 11 is then folded across the uppersurface of the bat 12 at fold point Ila shown in FIG. 4, enclosing thecable 14 and overlapping to bring the opposite edges of the net 11 intojuxtaposed relation. Net 11 thus forms a tubular sleeve enclosing thebat 12, with a heat-sealed or stitched edge seam joining these twojuxtaposed net edges along the boom edge 17 shown in FIGS. 4 and 5, onthe opposite edge of the elongated bat 12 from the edge beside whichcable 14 is laid. If desired a comparable seam may be stitched orheat-sealed between cable 14 and bat 12 to form a small cable hem orpocket positioning the cable along the aligned edges of all of the bats12 along the entire length of the boom 10.

The longitudinal spacing of the bats 12 within the tubular sleeve 11 ismaintained by the formation of transverse seams between the bats 12. Asshown in FIG. 4, these seams are preferably formed at the time the boomis fabricated. As the net 11 passing the fold point 11a is formed into asleeve by the sewn or heat-sealed seam 17 along the full length of thebat 12, a pair of transverse seams are preferably formed. The first is arear end seam 18 extending transversely across the tubular sleeve II ata point directly behind the bat l2, brining its upper and lower surfacesinto juxtaposition and stitching or heat-sealing them together along theflattened tubular sleeve toward the next bat 12, a frontend seam 19likewise extends transversely across the flattened sleeve to form theforward edge of a pocket enclosing the next bat 12, as shown in FIG. 4.

The seam l8 and 19 are spaced apart longitudinally by a distancesufficient to permit the boom to be accordion-folded in a stack such asstack 28 shown in FIG. 2 for storage and shipping. The distance betweenseams 18 and 19 should preferably be at least equal to the thickness ofbats 12 to permit this accordion-folding. Cable 14 may be caught atseams 18 and 19 if desired.

Suitable end fittings such as towing loops or shackles are preferablyjoined to the extreme ends of the cable 14 by swaged thimble fittings,eye splices or other common wire rope connection techniques.

As shown in FIG. 1, the completed boom is preferably deployed across themajor part if not the entire width of a flowing body of water at a pointdownstream from the transfer terminal at which petroleum products areloaded or unloaded from vessels where spills may occur. Thus in FIG. 1 atanker 20 is shown in oil transfer position beside a dock 21, surroundedby an oil spill boom 22. Arrows 23 show the direction of the prevailingcurrent passing the installation and the compressible collection boom ofthe present invention is shown deployed extending partway across thewaterway from one shore toward the opposite shore at a point downstreamfrom the tanker 20, positioned to receive oil carried downstream by thecurrent 23.

As shown in FIG. 2, after an oil film has been brought into contact withthe collection boom 10 by the prevailing current and after all or themajor portion of the oil film carried by the current 23 has been caughtand collected in the interstitial spaces between the loosely mattedfibers of the bats 12 along the length of the boom 10, the boom may bewithdrawn from the waterway by such means as the pinch roll oilseparation apparatus illustrated schematically in FIG. 2. In this figurepinch rolls 24 and 26 which may be powered to draw between themselvesthe compressible boom 10 are shown in power driven operation and theboom 10 is moving from the water between the pinch rolls 24 and 26 whichhave the effect of compressing each of the bats 12 in turn as these batsare drawn between the pinch rolls. As a result a large portion of thecollected oil is squeezed out of the compressible bats 12 into a sump 27beneath the pinch rolls. The squeezed collection boom 10 issuing fromthe pinch rolls is preferably accordion-folded in a storage stack 28near the shore 29 where it is ready for prompt deployment in the eventof another oil spill.

Cable 14 provides unusually high strength to the fibrous polymerstructure formed by the tubular net sleeve 11 and the lightweightcompressible bats 12, serving to position the boom in the shape andconfiguration and in the direction desired for optimum oil-collectingperformance.

In the alternative forms of the invention shown in FIGS. 6, 7 and 8, theoil-collection material is a slab of a different, highlyporous polymerstructure known as fully reticulated open-cell foam, preferably formedof polyurethane. This material is formed by exposing open cell polymerfoam to heat or chemical action, which has the effect of partiallydestroying, melting, fusing or vaporizing the polymer cell walls betweenthe open cells, further increasing the porosity and oil collectingcapability of this material. This elongated oil-collecting slab may beformed as an endless belt 31 (FIG. 6) or as a greatly elongated boom 32(FIG. 7).

The hydrophobic character of polyurethane foam, coupled with its lightweight and the rather high specific gravity of the urethane cell walls,normally ranging between 1.00 and 1.20, provide unusually effectiveoil-collecting action. After depbyment on an oil film or slick, thelightweight elongated foam slab 31 or 32 slowly sinks, and its waterlineslowly rises through the internal cells as air filling the internalporosities and cells is progressively displaced by the supportingliquid. Floating oil forms the topmost layer of the liquid exposed toall cell walls, progressively forming an overlying layer or coatingthereon as the foam slab sinks, while water does not adhere to thehydrophobic urethane surfaces.

As the slab 31 or 32 reaches substantially total immersion, smallpockets of air remaining entrapped in blind ends of a few passageways inthe foam structure often provide sufficient slight buoyancy,supplementing that of the collected oil, to prevent further sinking orcomplete submergence of the slabs 31 or 32.

When the slab is withdrawn from the spill or film-covered reservoir oranchorage, water drains freely from the interstices of the foamstructure, while the oil remains as a deposited layer or coating on theinterstitial cell walls.

Fully-reticulated open cell polyurethane foam may be fabricated in anelongated slab 2 inches thick, twelve inches wide and up to 60 feetlong, for example. The belt 31 of FIG. 6 or the elongated boom 32 ofFIG. 7 may be formed of one or more of such slabs. When several slabsare joined endwise to form a longer assembly, they may have their endsbonded together by cementing, heating or vibratory bonding techniques.

The belt 31 shown in FIG. 6 is formed as an elongated, continuous slabof such fully reticulated open cell polyurethane foam material, one endof which is immersed in the body of fluid 33 on which a layer offloating oil 34 resides. The opposite end of the belt 31 is interposedbetween a pair of pinch rolls 36 and 37 cooperating with sump 38 forpower driven squeezing of the compressible foam slab belt 31, operatingin the same manner as the pinch roll assembly 24-26 of FIG. 2 to recoverand collect the oil carried from the slick by belt 31.

In this embodiment illustrated in FIG. 6 however, an elongated,continuous foam slab belt 31 is continuously returned from the pinchroll assembly 36-37 back into the fluid reservoir 33 for continuousrecycling immersion, withdrawal and pinch roll oil squeezing recoveryoperations.

A two-part boom assembly 32 is illustrated in FIG. 7, comprising an oilcollection slab 39 having removably mounted thereon an overlying buoyantslab 41 of such buoyant flotation material as closed cell polyethylenefoam, for example. Cooperating strips or patches of Velcro material 45ccmented to the facing surfaces of the two foam slabs 39 and 41 may beemployed to secure these slabs in detachable facing relation, providingthe two-part assembly shown in FIG. 7.

In the lower righthand corner of FIG. 7, the oil collection slab 39 isshown immersed in the fluid reservoir while the attached buoyant slab 41floats on the surface of the reservoir. The assembly 32 is shown beingdrawn toward a pair of pinch rolls 42 and 43 above a sump 44, and as theassembly 32 approaches these pinch rolls the overlying buoyant slablayer 41 is peeled from the upper surface of the oil collection slab 39and diverted to by-pass the pinch rolls as indicated in FIG. 7.

The oil collection slab 39 passes between the pinch rolls 42 and 43 forcompressible squeezing to force out and remove collected oil, whichdrains from the pinch roll assembly 42- 43 into sump 44. The two slabs39 and 41 are then directed to be rejoined in facing relationship, andthey are directed through a second pair of re-mounting pinch rolls 46and 47 providing sufiicient compression force to squeeze slab 41 andslab 39 together into close juxtaposition, rejoining their respectiveVelcro strips or patches 45 and thus remounting the buoyant slab 41overlying the oil collection slab 39 to reassemble the oil collectionboom 32 ready for redeployment. When it is redeployed, the oilcollection slab 39 must be suspended beneath buoyant slab 41 on thewater-engaging underside of the assembly 32 for reimmersion, againdescending through the oil slick to perform the oil collection operationdescribed above. For this purpose, a half twist is customarily given tothe rejoined assembly 32, as shown in the upper portion of FIG. 7, andsuitable guide rolls may be employed for this purpose if desired.

Other buoyant flotation units may be formed on the compressible slab 39if desired. For example, as shown in FIG. 8, solid blocks 48 of highlyresilient compressible buoyant foam, such as polyethylene foam, may becemented as abutting strips along the edges of an oil collection slab 39which is formed of such material as fully-reticulated open cellpolyurethane foam, thus producing a unitary foam slab assembly 49 whichmay be directed between the pinch rolls 42-43 in order to express theoil collected in the central open cell oil collecting foam portion 39.This unitary assembly 49 avoids the need for the separation andrecombination of two individual layers like those forming the assembly32. in the unitary assembly shown in FIG. 8, the width and thickness ofthe buoyant flotation foam strips 48 are selected to suspend thecollection slab 39 at the desired immersion depth, with due regard tothe anticipated immersion period and the selection between the belt orthe elongated boom configurations illustrated in FIG. 6 and FIG. 7 asalternative forms of the fabricated structure to be employed.

The recycled belt 31 of FIG. 6 is customarily immersed for only a briefperiod during each cycle, and buoyant suspension of the oil collectionslab material is less necessary in this belt 31 embodiment than it is inthe elongated boom illustrated in FIGS. 1 4 5 and 7, which may remainexposed to the elements, deployed upon the surface of the slick coatedreservoir, for a considerable period of time between oil recoverysqueezing pinch r'oll operations. For maximum effectiveness, theelongated booms are customarily buoyantly positioned and maintained bytheir flotation material at a final equilibrium level closely coincidingwith the oil slick surface, in order to achieve maximum interstitialcell wall exposure to floating oil over the entire vertical height ofslab 39 during the gradual settling immersion of the boom assembly.

Since the foregoing description and drawings are merely illustrative,the scope of the invention has been broadly stated herein and it shouldbe liberally interpreted to secure the benefit of all equivalents towhich the invention is fairly entitled.

What is claimed is:

l. A resilient depressible oil collection boom for collection andremoval of oil from the surface of a fluid reservoir comprising:

A. a plurality of thin, flat, elongated bats of highly porous andresiliently depressible material having intercommunicating intersticesextending therethrough,

B. associated deployment means including an elongated tubular net sleevepositioning the bats juxtaposed with the surface of the fluid reservoir,with said bats being arrayed inside the length of the sleeve,

C. oil recovery expressing means operatively associated with the sleeveand positioned to depress successive portions of the bats, expellingaccumulated oil from the interstices of the depressed portions of thebats,

D. spacing means maintaining the adjacent bats longitudinally spacedapart by distances at least double their thickness, to permitaccordion-folding of the boom,

E. a tension-bearing cable extending longitudinally beside said batsalong the length of said sleeve, and

F. terminal fittings secured to the ends of the cable near thecorresponding ends of the tubular sleeve.

2. The boom defined in claim 1, wherein the net sleeve is formed ofpolymer fibers.

3. The boom defined in claim 1, wherein each elongated bat is formed ofa randomly oriented mass of polymer fibers.

4. The boom defined in claim 1, wherein each elongated bat is formed ofa mass of blown polymer film material.

5. The boom defined in claim 1, wherein said spacing means includetransverse seams flattening the tubular net sleeve between adjacentbats.

6. The boom defined in claim 1, wherein the cable is formed as a lengthof stainless steel wire rope.

2. The boom defined in claim 1, wherein the net sleeve is formed ofpolymer fibers.
 3. The boom defined in claim 1, wherein each elongatedbat is formed of a randomly oriented mass of polymer fibers.
 4. The boomdefined in claim 1, wherein each elongated bat is formed of a mass ofblown polymer film material.
 5. The boom defined in claim 1, whereinsaid spacing means include transverse seams flattening the tubular netsleeve between adjacent bats.
 6. The boom defined in claim 1, whereinthe cable is formed as a length of stainless steel wire rope.